1. Field of the Invention
The present invention relates to technology for interfering unauthorized copy of visual images shown on a screen of a visual image system.
2. Description of the Related Art
Following technique is disclosed as means to interfere such an unauthorized copy. The technique has been developed to utilize difference between visual characteristic of human eyes and image characteristic of imaging apparatus such as cameras, and employs infrared light to realize means to interfering the unauthorized copy. More specifically, infrared light is projected onto a screen surface from an infrared light projector disposed at a vicinity of an visual image projector or other remote position so as that infrared light reflected on the screen surface can be incident into the imaging apparatus of a person conducting the unauthorized act of copying the visual image appearing on the screen. In other words, an infrared light visual image, which is irrelevant to the main feature of visual images, is inevitably recorded on the visual image that is obtained in the unauthorized manner. Accordingly, overall quality of visual images recorded through the unauthorized manner are degraded. Sometime, such a degraded visual image enables to determine a location where the unauthorized act is taken place. Of course, viewer/audiences would not be affected by the interfering means and can enjoy the feature presentation of visual images appeared on the screen since infrared light can not be recognized by human eyes.
However, a reflection ratio of infrared light in a conventional cinema screen is not high enough. Accordingly, it is difficult to materialize desirable effect in a conventional system described above because of the low reflection ratio in the cinema screen as well as lengthy infrared light path between the screen and the infrared light projector disposed at the vicinity of the visual image projector. Further, there is a technical problem of that relatively high output power is required for the infrared projector so as to provide any significant effects on the visual images that are illegally recorded.
The present invention addresses the above-mentioned problems. It would be desirable to provide a practical technique capable of producing equal or more effective prevention effect than the conventional one while using an infrared light projector apparatus of a lower power.
According to the present invention, following means are provided.
(A) As a first means, the following technique is provided. In the technique, infrared light is projected to a viewer/audience direction from one or more infrared light projector means disposed at a screen side whereby enabling the infrared light to be incident into imaging means of a person conducting the unauthorized act. In embodiments of the present invention, the infrared light projector means may be realized in various configurations that include an infrared light projector apparatus, an infrared light projector, an infrared light emitting diode or any other device/apparatus/system capable of projecting infrared light. Furthermore, in embodiment of the present invention, the imaging means may be a camera, camcorder, video recorder or any other device/system comprising an image sensor capable of obtaining image data. The technique will eliminate needs of reflecting infrared light projected onto a screen surface of poor reflection ratio. Accordingly, the projected infrared light may be effectively incident into the imaging means of a person conducting the unauthorized act. That is, ample intensity of the infrared light may be radiated into the imaging means even when the low power infrared light projector apparatus is used.
(B) As a second means, another technique is provided. In the another technique, infrared light is actively reflected by an infrared light reflection means so as that the reflected infrared light may be incident into imaging means of a person conducting the unauthorized act. In embodiments of the present invention, the infrared light reflection means may be an infrared light mirror or any other device/apparatus/member capable of reflecting infrared light. The technique also will eliminate needs of reflecting infrared light projected onto a screen surface of poor reflection ratio. Accordingly, the projected infrared light may be effectively incident into the imaging means of a person conducting the unauthorized act. That is, ample intensity of the infrared light may be incident into the imaging means even when the low power infrared light projector apparatus is used.
(C) As a third means, still another technique is provided. In the still another technique, infrared light is intermittently emitted instead of continuous emission. Various advantages are realized by the intermittent emission. For example, a location in which the visual image piracy was taken place may be identified in case that the infrared light intermittent emission is outputted in accordance with a predetermined information. Alternatively, an emission intensity of infrared light may be frequently changed whereby enabling to degrade quality of visual images illegally recorded so much as that viewing of visual images recorded in the unauthorized manner becomes impossible due to the rapid change of intensity level.
(D) As a fourth means, still another technique is provided. In the still another technique, infrared light is selectively projected onto an area or areas of the screen surface, in which brightness is lower (for example, area or time period having a brightness of the screen surface equal or less than a predetermined value). The technique allows to emit or increase an amount of infrared light in a part where an amount of the visual image light is low whereby enabling to increase relative effects of the infrared light. Accordingly, more effective prevention of the visual image piracy may be possible. Further, in case that certain information is superposed on the infrared light, such information is surely recorded on the visual images illegally recorded.
(E) As a fifth means, still another technique is provided. In the still another technique, infrared light is projected from a plurality of infrared light projector means disposed in the vicinity of a screen whereby having the reflected infrared light be incident into imaging means of a person conducting the unauthorized act. The technique uses the similar principle as that of the conventional technique except the infrared light projector apparatus in the present embodiment are selectively disposed in the vicinity of the screen. Accordingly, the reflected infrared light may be significantly increased whereby enabling to promote the prevention effect further.